MTL True-Scale Couplers - Recommended Height?

[wcfn100]

Since I don't think anyone has said it yet.....

Is there a possibility of establishing a NEW standard?

MT couplers height now is too high.

Can you explain? 

We covered this already in this thread I believe and the MTL coupler centers (as listed on their site) are within .06" to .145" prototype inches depending if the correct MLT number is .216" or 5.5mm (both are listed).  Are the actual couplers different than what MTL says?


Jason

[u18b]

Jason,
I don't see what I'm mentioning in this thread.  I guess I'm missing it-  sorry if I am.

If it was in another thread, sorry also.

I don't have any specific measurements.
I'm thinking more in line with bigger simple observations.
Like the following.

Fact 1.  The original height of an N scale car was a bit high in order to accommodate the huge pizza cutter flanges in the 60s and 70s.
Fact 2.  Now we have better flanges.
Fact 3.  Some members of this board (like Bryan Bussey) have a passion for escaping the prior restraints of old "N gage" and want lower cars that are closer to prototypical height.
Fact 4.  But when you lower a car, now you have to RAISE the coupler head of a body mounted coupler (Don't you?  usually?) in order to get the coupler at the age old height that we have lived with in N scale and that is now on all of our equipment.

But is the center of the age old standard (like on a MT height gage) the same height as the prototype?  (I don't know).

If it is, then my query is moot.

But if it is high as compared with the protoptype, I was suggesting that this closer to scale coupler is an opportunity to possibly lowering the coupler head to a more prototypical height.

Sorry if my thinking is all washed up on this.

It just seems like lower cars with lower couplers--- all closer to actual prototype practice would lead a part of N scale a step closer to something closer to true scale.  At least it would make the Proto160 crowd happier.

[Missaberoad]

Ron, Here's the quotes in question from the other thread...

I haven't taken any measurements to confirm, but it would seem that the Micro-trains height gauge is pretty close to the prototype measurement.
The center line being close to prototype means that the top of an N scale coupler will be too high due to it being oversized, but a true-scale at that center line should correct that issue...

This actually brings up a good question... What is the height of a prototype couper and how does that relate to the current standard?

2' 10-1/2" to center which would be 0.215625".  The MTL sheet says their centerline is .216" but that could use a real measurement check probably.

Jason

Interestingly, "Model Railroader Cyclopedia - Volume 1" gives the height of the center of the coupler face above the rail as 33-1/2" for freight engines and 34-1/2" for passenger engines.  For N scale, those become 0.209" and 0.216".  The NMRA standard is 0.216".

[wcfn100]

Fact 4.  But when you lower a car, now you have to RAISE the coupler head of a body mounted coupler (Don't you?  usually?) in order to get the coupler at the age old height that we have lived with in N scale and that is now on all of our equipment.

What isn't accounted for here is the clearance between the truck mounted coupler box and the floor of the car.  Looking at it in a different way, if you take the coupler off the truck and mount it to the floor of the car, it gets raised.  But then when you lower the car, it gets lowered back down.  Not always a wash depending on the car but I'm just showing the concept.

But like I said previous, going by the numbers that MTL says in their instructions, their coupler center line is correct to the prototype.  But I don't know if couplers in the wild actually match the MTL specs.  Thx Ryan for finding that.

I feel a shapeways project for someone to create a height gauge that will natively accept the True-Scale coupler.

Jason

[nkalanaga]

For one gauge, you could come pretty close with stacked styrene strips and possibly a paper shim or two.

[u18b]

Thanks for the answers guys.

[C855B]

Did you (or would you please) measure the interior height and width of the box? Also the diameter & setback of the pivot pin?

Here you go, everything +/- 0.001":

Box internal is 0.163" x 0.060".*

Pin is 0.047", setback 0.015".

* - Important note: there are posts protruding into the sides of the face opening reducing the width to 0.125". I have a hunch this is operational, and quash my idea of cutting back the notches for "drop-in" situations like that Atlas S-2 I was working with.

Also...

According to the MT-1055 alignment gauge, rail top to coupler center is 0.230". So that would be 0.014" high versus what is being discussed as prototype and/or spec.

[wcfn100]

Also...

According to the MT-1055 alignment gauge, rail top to coupler center is 0.230". So that would be 0.014" high versus what is being discussed as prototype and/or spec.

Well that's not good.  The instructions for the 1055 still show .216" as what the center line should be.

Jason

[MichaelWinicki]

Heh heh. Yeah, I know... but anybody wanting to do an "all at once" conversion from truck-mounted Magna-Matics to body-mounted True-Scale is going to be in for a real shock when they suddenly can't randomly mix-and-match cars on their 9-3/4" curves. (Actually, from what I'm seeing so far, given the limited lateral range I have my doubts about reliable operation on radii under 18" on any combination of cars. Open to being proven wrong.)

Minimum radius requirements for these couplers... Interesting to see how small of a radius will work with these new couplers.

Maybe a truck-mounted version wouldn't be a bad idea!

[ednadolski]

Here you go, everything +/- 0.001":

Box internal is 0.163" x 0.060".*

Pin is 0.047", setback 0.015".

* - Important note: there are posts protruding into the sides of the face opening reducing the width to 0.125". I have a hunch this is operational, and quash my idea of cutting back the notches for "drop-in" situations like that Atlas S-2 I was working with.

Thanks for posting!  Just so I understand, this is the long-shank version, is that correct?

This looks like it wants a box that internally is the 0.163" wide in order to provide room for the side springs.  The front opening could be the narrower 0.125" for appearances sake, but if any smaller it would start to restrict operation on curves.

The 0.047 pin diameter seems about right to mount with a 00-90 screw if desired.  On that setback, did you measure to the surface of the pin, or to its center?

Ed

[Cajonpassfan]

Minimum radius requirements for these couplers... Interesting to see how small of a radius will work with these new couplers.

Maybe a truck-mounted version wouldn't be a bad idea!

Shirley, you must be jesting, yes?
And maybe add some pizzacutters while at it to make sure the car tracks right ?
As to the minimum radius, wouldn't that be in part a function of carbody length?
I'm still waiting form mine to arrive, so I'm just speculating...
Otto K.

[C855B]

... this is the long-shank version, is that correct?... did you measure to the surface of the pin, or to its center?

No, short-shank. Setback from the face on the long-shank is 0.065". This dimension is also to the surface of the pin, so calculate accordingly.

Worthwhile mentioning here that the "notches" I was talking about (relative to the S-2) are longer on the long-shank, but still not as deep as the 1015 or Accumate. It would probably be slightly easier to install the long-shank version on the switcher, but the modification then becomes a new hole for the mounting screw. While the longer box would not interfere with the truck swing, I have a slight concern about drilling a new hole so close to the stock location.

[garethashenden]

Here you go, everything +/- 0.001":

Box internal is 0.163" x 0.060".*

Pin is 0.047", setback 0.015".

* - Important note: there are posts protruding into the sides of the face opening reducing the width to 0.125". I have a hunch this is operational, and quash my idea of cutting back the notches for "drop-in" situations like that Atlas S-2 I was working with.

Also...

According to the MT-1055 alignment gauge, rail top to coupler center is 0.230". So that would be 0.014" high versus what is being discussed as prototype and/or spec.

I always thought that the gauge was high. Truck mounted couplers and factory installed body mounts all are lower than the gauge I have. Because of this I have tended to use a truck mounted coupler as a gauge.

[C855B]

I always thought that the gauge was high. Truck mounted couplers and factory installed body mounts all are lower than the gauge I have. Because of this I have tended to use a truck mounted coupler as a gauge.

Well that certainly sucks. I never thought about it that way, and was taking the gauge as gospel when mounting on locos, especially the conversions from Rapido hooks.

But sure enough, I take any unmodified MTL or the hundred or so cars converted to MTL trucks, and they're all "low" compared to the gauge. I even took the gauge apart again just to be 100% the coupler box wasn't upside down and mounted on the thicker top, but no, it is correctly assembled.

Damn. 

[GaryHinshaw]

I've noticed this too.  Whenever I mount LEZ couplers, I make sure they line up with the centre of an MTL truck-mounted coupler, and not the standards gauge.